Field-flow fractionation devices

Battu, S. Delebasse, S. Bosgiraud, C. Cardot, P.J. Sedimentation field-flow fractionation device cleaning. 

Figure 7.3.21. Field-flow fractionation (FFF). (a) Basic configuration of field-flow fractionation device and the detector response to a sample, (b) Retention ratio of species i vs. retention parameter X. (c) Schematic for flow field-flow fractionation with a cros ow. (d) Fhysical configuration/dimensions of a FFF channel with inlet/outlet. (e) Configuration of the channel in sedimentation FFF. (After Giddings (1993).)...

Lao, A.I.K., Trau, D., Hsing, I., Miniaturized flow fractionation device assisted by a pulsed electric field for nanoparticle separation. Anal. Chem. 2002, 74, 5364-5369. 

Fig. 6.5 Field flow fractionation (FFF) of aggregated adenovirus sample. The figure shows the mass of adenovirus (cumulative and non-cumula-tive) as a function of particle diameter as determined by FFF using a Focus AF2000 device (Post-...

An integrated module for on-line sample pre-analytical treatment and/or clean-up could be also included in the device. With this respect, field-flow fractionation (FFF) techniques, which can separate analytes based on their morphological characteristics (size, shape and superficial properties) can be exploited to develop pre-analytical modules for cells or macromolecules (e.g., proteins, protein complexes or adducts) fractionation, thus providing a selectively enriched fraction for the analysis. 

Thermophoresis is applied in industry for the separation of (large) molecules or small particles from their solvent in the so-called thermal field-flow fractioning (TFFF) [13]. A downscaled version of this process to microscopic scales demonstrated thermophoretic separation on microscopic scales [14, 15]. The advantage of using the very small confinement in a microfluidic device is that the separation times can be reduced, so that thermophoretic separation can be used. Braun and Libchaber [16] use a combination of thermophoresis and convection to concentrate DNA samples. The disadvantage of this approach is that it is a batch process. 

Schematic of field-flow lEF of mitochondria, (b) Photograph of a microfabricated device before final assembly (c) enlarged view of the fractionation end of the device. The device consists of electroplated gold electrodes and microfluidic channels formed in a photopattemable...

One characteristic of shear banded flow is the presence of fluctuations in the flow field. Such fluctuations also occur in some glassy colloidal materials at colloid volume fractions close to the glass transition. One such system is the soft gel formed by crowded monodisperse multiarm (122) star 1,4-polybutadienes in decane. Using NMR velocimetry Holmes et al. [23] found evidence for fluctuations in the flow behavior across the gap of a wide gap concentric cylindrical Couette device, in association with a degree of apparent slip at the inner wall. The timescale of these fluctuations appeared to be rapid (with respect to the measurement time per shear rate in the flow curve), in the order of tens to hundreds of milliseconds. As a result, the velocity distributions, measured at different points across the cell, exhibited bimodal behavior, as apparent in Figure 2.8.13. These workers interpreted their data... 

This design practically or to a considerable extent eliminates particles collisions in the separation zone, which sharpens separation. As the flow field in the chamber has no inherent vortexes the device has lower air resistance and energy consumption. Several prototypes of this classifier were used in phosphate industry for separation of crushed phosphate ore at 1 mm cut size. One such plant with output of 251 per hour and pressure drop of 800-900 Pa yielded 96-98% cleanness of fines and 78-85% of coarse fraction [8],... 

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